1. Field of the Invention
The present invention is directed to an indirectly fired vertical shaft furnace suitable for use as a volatilizing furnace for recovering metals from their ores, a drying or roasting furnace for crops or a hot air heating furnace.
2. Prior Art
The present invention is an improvement over the Jackson et al U.S. Pat. No. 3,876,189 directed to an automatic feedupright ore furnace. The furnace disclosed in this patent was provided with a cylindrical steel retort of a suitable fire resistant alloy but the outer heating chamber which completely surrounded the retort was constructed of firebrick. The lower portion of the cylindrical steel retort was also covered with a layer of firebrick to define an annular flame chamber and since the flame jet was directed radially inwardly through the outer wall, it was necessary to provide an upwardly angled flame shield for deflecting the heat upwardly into the annular heating chamber surrounding the steel retort. In the Jackson et al patent a metal vapor collector conduit was coaxially located within the retort and was provided with spirally arranged apertures for collecting metal vapor under transverse channels, which extended radially outwardly from the conduit above each of the apertures and which were supported underneath by substantially triangular gussets. Air was supplied to the lower end of the retort by two diametrically opposed conduits extending radially inwardly through the firebrick walls of the combustion chamber and the supply of air to the centrally located collector conduit was controlled by a damper at the lower end of the collector conduit which extended vertically downwardly through the bottom of the furnace.
Thus, the Jackson et al patent provided an improved metal volatilization furnace for extracting metal from an ore which was continuously tumbled downwardly through the furnace in a spiral path without the need of any moving parts within the furnace.